Drafting aid

ABSTRACT

THE DISCLOSURE CONCERNS A DRAFTING AID. SPECIFICALLY, A HOLDING DEVICE FOR FITTING WITH A T SQUARE FOR THE PURPOSE OF HOLDING THE T SQUARE IN NORMAL WORKING POSITION, I.E., SQUARE TO THE BOARD. THE DEVICE INCLUDES A SPRING URGED ROLLER INTERCONNECTED WITH A BAR CLAMPING MEANS WHICH FIXES THE PARTS IN POSITION ON THE T SQUARE. NORMAL POSITION MAINTAINS THE DESIRED BOARD SQUARENESS IN USE, BUT ALSO ALLOWS READY RELEASE OF THE ROLLER WITHOUT DISMOUNTING, WHEREBY THE T SQUARE WITH THE DEVICE THEREON MAY BE REMOVED AND REPLACED AT WILL.

June 15971 J. M. STEWART v I 3,585,725

DRAFTING AID Filed Nov 4, 1969 2 Sheets-Sheet 1 FIG.5

INVENTOR JAMES M. STEWART ATTORNE Y3 DRAFTING AID 2 Sheets-Sheet 2 Filed Nov. 4, 1969 FIG.4

FIG.3

INVENTOR JAMES M. STEWART United States Patent 3,585,725 DRAFTING AID James M. Stewart, 2800 N. Flagler Drive, West Palm Beach, Fla. 33407 Filed Nov. 4, 1969, Ser. No. 873,977

Int. Cl. B43l 7/04 US. C]. 33-80 2 Claims ABSTRACT OF THE DISCLOSURE The disclosure concerns a drafting aid. Specifically, a holding device for fitting with a T square for the purpose of holding the T square in normal working position, 1.e., square to the board. The device includes 'a spring urged roller interconnected with a bar clamping means which fixes the parts in position on the T square. Normal position maintains the desired board squareness in use, but also allows ready release of the roller without dismounting, whereby the T square with the device thereon may be removed and replaced at will.

This invention relates to drafting equipment. More particularly, the invention relates to means for malntaining a T square firmly in square position relative to the drawing board with which it is used so that it is not necessary for the draftsman constantly to be holdlng the T square in position, and/or adjusting it to surely attain proper position. Additionally, the invention provides such a means which is readily adjustable along the length of the T square in order that the assembly may readily be employed across the width of the board as well as in the normal lengthwise position; or, in order that the assembly may be employed on boards of different sizes. Also, the invention provides such an assembly which permits fitting to and removal from the drafting board with utmost ease, and without attention to readjustment of the assembly at any time following the adjustment which is initially made at the time the T square is positioned and made secure. It will be understood that the T square is readily movable relative to the board surface in the normal manner, while also remaining in square position during such movement. The holding means of this invention does not require any modifications to be made to the drawing board, such as special tracks, grooves, or the like. The means attaches to the T square and effects its holding action at a point entirely beyond the drawing board surface. Thus, it does not at anytime interfere with the work of the draftsman.

The holding means of this invention may be economically produced, as by injection molding from common plastics. Its association with the T square requires no special T-square design or modifications.

The position holding device of this invention is illustrated by drawings wherein:

FIG. 1 is a top plan view of a drawing board and T square employing the invention. Phantom lines indicate permissible cross board positioning;

FIG. 2 is an enlarged top plan view of the holding device, partially broken away;

FIG. 3 is a bottom plan view of the holding device;

FIG. 4 is a partial sectional view, in horizontal plane, of the holding device; and

FIG. 5 is a perspective view of a part insertable in the holding device for size adjustment purposes.

Referring to the drawings, particularly FIG. 1, numeral denotes a conventional drawing board, numeral 12 denotes a conventional T square, and numeral 14 denotes the device of this invention in its operative position relative to the T square and board.

Referring to the more illustrative figures of the drawings, numeral 16 denotes the main body of the position holding device, this body comprising a pair of parallel side walls and end walls, forming a rectangular sleeve which fits about the T square. As seen in the drawings, the upper end wall is provided with a bore 18 extending into the open sleeve area. Bore 18 is interiorly threaded and it accommodates a threaded adjustment and locking shaft 20 carrying a knob 22, by which it is turned, and a bar 24 which moves with the shaft and normally is brought to bear upon the T square edge surface. As will be understood as bar 24 is moved inwardly it contacts the T-square edge, thereby locking the device in any desired position.

Mounted on a rotatable shaft 26, and on the bottom side of the sleeve body, is a lever arm 28 which carries a freely rotating roller 29 supported on pin 30. Lever 28 is normally urged in the direction of the drawing board edge by spring 32, which is mounted upon brackets 34 and 36. Extending away from brackets 34 and 36 are pins 38 and 40, which serve to maintain the spring in proper position and to limit movement of lever arm 28 when positioning the device relative to the drawing board edge. As will be understood, the more spring 32 is compressed, the greater the pressure which the roller exerts against the drawing board edge, against which it normally bears when the device is in operative locked position. However, it will be seen that the fullest possible compression would position the edge of the sleeve directly against the board surface, in which position it tends to firmly lock the T square against desirable and normal movement relative to the board. Thus, the lever is limited in its movement so as to require some projection of the roller surface beyond the bottom Side wall when the spring is placed under compression during positioning of the device. As will be understood, the length of the pins controls the extent of such projection; and spring strength is selected to provide the desired pressure exerted through the roller upon the board edge. Lever arm 28 is limited in its opposite movement by pin 42, which it contacts when the device is not in use.

Numeral 44 denotes a second lever arm mounted on the top side of the device, which is manipulated by hand in releasing roller pressure upon the board edge so as to permit the T square to be taken from the board without difiiculty. Lever arm 44 is fixedly mounted on shaft 26, as is lever arm. 28, and, therefore, movement of one arm effects simultaneous movement of the other. Lever arm 44 is provided with an upstanding surface 46 which permits it to be thumb-contacted for movement. A complementary surface 48 is fixed to upper sidewall 50, permitting grasping of the two surfaces in the fingers when releasing the roller pressure and removing the T square from the drawing board. As should be apparent, movement of the thumb piece toward surface 48 effects movement of the roller away from the board edge.

It is pointed out that in positioning the holding device on the T square for normal use, the spring is usually not compressed to its fullest extent, i.e., to the extent that the ends of pins 38 and 40 are in contact with each other; rather, it is desirable that some small distance exist between the pin ends so that the spring may be further compressed. Roller 29' may then be pulled away from board contact by finger manipulation of surface 46, thus permitting free lifting of the T square relative to the board in the course of normal T square removal, while not necessitating removal of the holding device from the T square.

Somewhat in contrast to the foregoing, it is pointed out that the position of roller 29 may be made adjustable, for example by substituting a rotary pin for fixed pin 34, so that the lower long edge '52 may be brought squarely against the board edge and thereby actually frictionally ice lock the T square in a fixed position for a period of time desirable in consideration of a particular drawing to be made.

In associating the holding device with the T square and board, it may be slid over the end of the T square, following which the T square is laid in square position relative to the board and there firmly hand held. The holding device is then slid along the T square and the roller 29 is brought into strong pressure contact with the board edge. Holding the assembly in such position, shaft 20 is rotated to press bar 24 into firm frictional engagement with the adjacent T-square edge thereby locking or securing the device in the desired position with the spring under compression and the roller against the board edge. Release of the device when desired will be apparent.

Referring to FIG. 5, element 54 constitutes a small insert for insertion at the end opposite the movable bar in order that the device may be more readily adapted to T squares of different widths. As will be appreciated, this element is not essential since shaft 20 may be lengthened as desired; however, use of the insert permits better positioning of the roller relative to the center line of the T square. The corner 54 which is reduced in thickness is provided in order to avoid engagement with the board edge. Element 52 is inserted between the side walls and pressed in to contact with the adjacent end wall at which point flanges 56 hold it in place.

What is claimed is:

1. A T-square positioning device comprising a rectangular sleeve conforming to the configuration of the T-square bar cross section; a securing bar in said sleeve adjacent one of its ends having means for moving it into holding engagement with an adjacent edge of the T square, thereby securing the device to the T-square bar; a shaft extending through one end of said sleeve carrying an upper and a lower lever arm on its opposite ends, the lower lever arm carrying a roller on its end opposite the shaft and said arm being spring-biased laterally of said sleeve in the direction of the T-square head enabling it to contact a drawing board edge surface; means for limiting roller movement in the direction away from said T-square head such that at least a segment of its body is always closer to said T-square head than said sleeve; said upper lever arm constituting a means for rotating said shaft and eifecting movement of said lower lever arm, whereby said roller may be moved from engagement with said board edge.

2. A device as claimed in claim 1 wherein said bar is provided with a threaded stud extending through the adjacent end wall in a threaded bore; said stud being provided with means to facilitate its rotation.

References Cited UNITED STATES PATENTS 2,995,823 8/1961 Bowen 33-80 FOREIGN PATENTS 921,617 11/1954 Germany 33 s0 702,594 1/1954 Great Britain 3380 LEONARD FORMAN, Primary Examiner C. E. PHILLIPS, Assistant Examiner 

